Fix bug when updating user email (#36058)

Fix #20390 

We should use `ReplacePrimaryEmailAddress` instead of
`AdminAddOrSetPrimaryEmailAddress` when modify user's email from admin
panel. And also we need a database transaction to keep deletion and
insertion succeed at the same time.

routers/web/admin/users.go

@@ -409,7 +409,7 @@ func EditUserPost(ctx *context.Context) {
 	}
 
 	if form.Email != "" {
-		if err := user_service.AdminAddOrSetPrimaryEmailAddress(ctx, u, form.Email); err != nil {
+		if err := user_service.ReplacePrimaryEmailAddress(ctx, u, form.Email); err != nil {
 			switch {
 			case user_model.IsErrEmailCharIsNotSupported(err), user_model.IsErrEmailInvalid(err):
 				ctx.Data["Err_Email"] = true